60th Anniversary of the Malta Historical Society : A Commemoration

The paper traces the survival of the archive of the Roman Inquisition in Malta (1561-1798) during the French republican occupation, between June 1798 and September 1800. The primary sources identified and utilised in the study enable a detailed understanding of the archive's content just months following the suppression of the tribunal on the island. The Maltese archive is among the major ones to survive to very substantial extent, even more so since the archive of the Congregation for the Doctrine of the Faith (formerly the Congregation of the Roman Inquisition) also holds a substantial collection of Malta material

Transforming triangulations on non planar-surfaces

We consider whether any two triangulations of a polygon or a point set on a non-planar surface with a given metric can be transformed into each other by a sequence of edge flips. The answer is negative in general with some remarkable exceptions, such as polygons on the cylinder, and on the flat torus, and certain configurations of points on the cylinder.Comment: 19 pages, 17 figures. This version has been accepted in the SIAM Journal on Discrete Mathematics. Keywords: Graph of triangulations, triangulations on surfaces, triangulations of polygons, edge fli

Analytical study of non Gaussian fluctuations in a stochastic scheme of autocatalytic reactions

A stochastic model of autocatalytic chemical reactions is studied both numerically and analytically. The van Kampen perturbative scheme is implemented, beyond the second order approximation, so to capture the non Gaussianity traits as displayed by the simulations. The method is targeted to the characterization of the third moments of the distribution of fluctuations, originating from a system of four populations in mutual interaction. The theory predictions agree well with the simulations, pointing to the validity of the van Kampen expansion beyond the conventional Gaussian solution.Comment: 15 pages, 8 figures, submitted to Phys. Rev.

The 5′-3′ exoribonuclease Pacman is required for normal male fertility and is dynamically localized in cytoplasmic particles in Drosophila testis cells

The exoribonuclease Xrn1 is widely recognised as a key component in the 5'-3' RNA degradation pathway. This enzyme is highly conserved between yeast and humans and is known to be involved in RNA interference and degradation of microRNAs as well as RNA turnover. In yeast and human tissue culture cells, Xrn1 has been shown to be a component of P-bodies (processing bodies), dynamic cytoplasmic granules where RNA degradation can take place. In this paper we show for the first time that Pacman, the Drosophila homologue of Xrn1, is localized in cytoplasmic particles in Drosophila testis cells. These particles are present in both the mitotically dividing spermatogonia derived from primordial stem cells and in the transcriptionally active spermatocytes. Pacman is co-localized with the decapping activator dDcp1 and the helicase Me31B (a Dhh1 homologue) in these particles, although this co-localization is not completely overlapping, suggesting that there are different compartments within these granules. Particles containing Pacman respond to stress and depletion of 5'-3' decay factors in the same way as yeast P-bodies, and therefore are likely to be sites of mRNA degradation or storage. Pacman is shown to be required for normal Drosophila spermatogenesis, suggesting that control of mRNA stability is crucial in the testis differentiation pathway

Orphaning Regimes: The Missing Link Between Flattened and Penetrating Slab Morphologies

Slab orphaning is a newly discovered phenomenological behavior, where the slab tip breaks off at the top of the lower mantle (~660 km depth) and is abandoned by its parent slab. Upon orphaning, subduction continues uninterrupted through the lateral motion of the parent slab above 660 km depth. In this work, we present a regime diagram for the range of conditions under which slabs can orphan at the top of the lower mantle. Our models show that a viscosity jump at 1,000 km depth not coincident with the endothermic phase change responsible for the 660 km seismic discontinuity, is necessary for orphaning as is the presence of a low viscosity channel between 660 and 1,000 km depth. We show that orphan slabs, similar to other deep slab morphologies, can be the end result for a wide range of physical parameters governing slab dynamics: slab orphaning persists across wide variations in slab dip, slab yield stress/strength, Clapeyron slope values, and overriding plate nature. The diversity in orphan slab sizes and orphaning periods is tied to the orphaning regime space, which describes a hitherto unexplored region between deflected and penetrating deep-subduction modes. Orphaning provides a simple dynamic link between the well-known deflection and penetration, and provides one possible way for slabs to switch from direct penetration to deflection, littering the mantle with abandoned fragments. Orphan slabs are therefore the intermediary between these two extensively studied slab morphologies

Photobioreactor Design and Fluid Dynamics

Photobioreactor design is a subject of great relevance for the attainment of a sustained development in modern technology,and has also considerable interest from the basic scientific and technologic point of view.The aim of the present review paper is presenting and comparing some of the recent attempts by the authors of modelling photosynthesis in reactors.A short inspection of the kinetic models proposed for photobioreactor design is done,and some examples of the integration of such kinetic models and bioreactor fluid dynamics in the modelling of photobioreactors are presented

Sampling bias in systems with structural heterogeneity and limited internal diffusion

Complex systems research is becomingly increasingly data-driven, particularly in the social and biological domains. Many of the systems from which sample data are collected feature structural heterogeneity at the mesoscopic scale (i.e. communities) and limited inter-community diffusion. Here we show that the interplay between these two features can yield a significant bias in the global characteristics inferred from the data. We present a general framework to quantify this bias, and derive an explicit corrective factor for a wide class of systems. Applying our analysis to a recent high-profile survey of conflict mortality in Iraq suggests a significant overestimate of deaths

The Order of St. John's galley squadron at sea

In the article, the name of the author is listed erroneously as Joseph A. Grima.In a scrupulously factual description of various aspects of life at sea on an Order's galley in the seventeenth century Mediterranean, Joseph F. Grima details the ship's movements in and out of harbour as well as in action, procedures relating to protocol and discipline, and also conditions of the crew on board, such as food provisions and medical services.peer-reviewe

The 5'-3' exoribonuclease pacman is required for epithelial sheet sealing in Drosophila and genetically interacts with the phosphatase puckered

Background information. Ribonucleases have been well studied in yeast and bacteria, but their biological significance to developmental processes in multicellular organisms is not well understood. However, there is increasing evidence that specific timed transcript degradation is critical for regulation of many cellular processes, including translational repression, nonsense-mediated decay and RNA interference. The Drosophila gene pacman is highly homologous to the major yeast exoribonuclease XRN1 and is the only known cytoplasmic 5′–3′ exoribonuclease in eukaryotes. To determine the effects of this exoribonuclease in development we have constructed a number of mutations in pacman by P-element excision and characterized the resulting phenotypes. Results. Mutations in pacman resulted in flies with a number of specific phenotypes, such as low viability, dull wings, crooked legs, failure of correct dorsal/thorax closure and defects in wound healing. The epithelial sheet movement involved in dorsal/thorax closure is a conserved morphogenetic process which is similar to that of hind-brain closure in vertebrates and wound healing in humans. As the JNK (c-Jun N-terminal kinase) signalling pathway is known to be involved in dorsal/thorax closure and wound healing, we tested whether pacman affects JNK signalling. Our experiments demonstrate that pacman genetically interacts with puckered, a phosphatase that negatively regulates the JNK signalling pathway. Conclusions. These results reveal that the 5′–3′ exoribonuclease pacman is required for a critical aspect of epithelial sheet sealing in Drosophila. Since these mutations result in specific phenotypes, our data suggest that the exoribonuclease Pacman targets a specific subset of mRNAs involved in this process. One of these targets could be a member of the JNK signalling pathway, although it is possible that a parallel pathway may instead be affected. The exoribonuclease pacman is highly conserved in all eukaryotes, therefore it is likely that it is involved in similar morphological processes, such as wound healing in human cells

The 5'-3' exoribonuclease Pacman (Xrn1) regulates expression of the heat shock protein Hsp67Bc and the microRNA miR-277-3p in Drosophila wing imaginal discs

Pacman/Xrn1 is a highly conserved exoribonuclease known to play a critical role in gene regulatory events such as control of mRNA stability, RNA interference and regulation via miRNAs. Although Pacman has been well studied in Drosophila tissue culture cells, the biologically relevant cellular pathways controlled by Pacman in natural tissues are unknown. This study shows that a hypomorphic mutation in pacman (pcm5) results in smaller wing imaginal discs. These tissues, found in the larva, are known to grow and differentiate to form wing and thorax structures in the adult fly. Using microarray analysis, followed by quantitative RT-PCR, we show that eight mRNAs were increased in level by >2 fold in the pcm5 mutant wing discs compared to the control. The levels of pre mRNAs were tested for five of these mRNAs; four did not increase in the pcm5 mutant, showing that they are regulated at the post-transcriptional level and therefore could be directly affected by Pacman. These transcripts include one that encodes the heat-shock protein Hsp67Bc, which is upregulated 11.9-fold at the post-transcriptional level and 2.3-fold at the protein level. One miRNA, miR-277-3p, is 5.6-fold downregulated at the post-transcriptional level in mutant discs, suggesting that Pacman affects its processing in this tissue. Together, these data show that a relatively small number of mRNAs and miRNAs substantially change in abundance in pacman mutant wing imaginal discs. Since Hsp67Bc is known to regulate autophagy and protein synthesis, it is possible that Pacman may control the growth of wing imaginal discs by regulating these processes